In the past, a device for detecting a facial direction etc., of a driver using an image capturing means provided in a vehicle has been known. For example, PLT 1 describes that the facial direction of the driver and the angular velocity in the facial direction are calculated from the image of the driver captured by an image capturing means and, if the facial direction of the driver is outside the range of capture of the image capturing means, the facial direction is estimated based on the angular velocity in the facial direction.